Fluorescence induction used to measure parathion toxicity in the marine dinoflagellate Prorocentrum micans: a possible model for biodetection.

The marine dinoflagellate Prorocentrum micans Ehrenberg was used as a test organism to determine the conditions of use of fluorescence induction kinetic measurements in the study of parathion phytotoxicity. Measurements were taken of the kinetics of slow and fast fluorescence induction in whole cells and isolated chloroplast fragments at various concentrations of parathion. In both types of induction, the addition of parathion greatly decreased the fluorescence yield, indicating either inhibition of electron transport or physical changes.

Chlorophyll fluorescence transients from the diatom Phaeodactylum tricornutum: relative rates of cyclic phosphorylation and chlororespiration.

In Phaeodactylum tricornutum cells kept 30 min in the dark, induction of fluorescence showed the well-known levels OIDPSMT. The decrease of MT was the most important when the intensity of excitation light was high. It was mainly due to the photochemical quenching.

Effects of light quality on chlorophyll-forms Ca 684, Ca 690 and Ca 699 of the diatom Phaeodactylum tricornutum.

Colored light modifies the relative concentration of chlorophyll-forms of the diatom Phaeodactylum tricornutum compared to white-light control. No change in the ratio carotenoids/chlorophylls was observed after 4 days exposure to green light (max: 530 nm), blue light (max: 470 nm) or red light (λ > 650 nm) of same intensity.However, the absorption spectra were modified, the content in Ca 684, Ca 690, Ca 699 forms increased in red and green light cultures and photosynthetic unit size of PS II decreased by 30% in green and blue light cultures.

Energy transfers from photosystem II to photosystem I in Cryptomonas rufescens (Cryptophyceae).

In Cryptomonas rufescens (Cryptophyceae), phycoerythrin located in the thylakoid lumen is the major accessory pigment. Oxygen action spectra prove phycoerythrin to be efficient in trapping light energy. The fluorescence excitation spectra at -196 degrees C obtained by the method of Butler and Kitajima (Butler, W.

Spectral properties of system I-deficient mutants of Chlamydomonas reinhardi. Possible occurrence of uphill energy transfer.

Chlamydomonas reinhardi mutants lacking the P-700-chlorophyll alpha-protein complex CPl, lack as well the long wavelength forms of chlorophyll Ca 691 and Ca 704 normally present in the absorption spectrum at -196 degrees C. These mutants do not display the 715 nm peak in the fluorescence emission spectrum at -196 degrees C. Studies of the System II action spectrum of one such mutant show an increase in the optical cross-section of the System II centers around 685 nm.